In the photographic field, it has been known to use a quaternary ammonium salt polymer as a mordant for fixing anionic dyes as disclosed in U.S. Pat. Nos. 3,709,690, 3,958,995 and 3,898,088, etc. However, polymers of this type have insufficient ability to hold mordanted dyes in a stable form, though exhibiting satisfactory mordanting property for dyes. In other words, photographic systems involving dye images mordanted by these polymer mordants suffer from a disadvantage in that mordanted dye images are susceptible to chemical change or decomposition due to irradiation with fluorescence or sunlight, etc.
On the other hand, British Pat. No. 2,056,101 and U.S. Pat. Nos. 4,115,124, 4,282,305 and 4,273,853, etc. disclose polymers having a tertiary imidazole ring in their side chains. Although these polymers have a property to maintain the mordanted dyes in a stable form against light, there is a problem that the mordanted dyes are susceptible to chemical change or decomposition due to temperature or humidity changes. In other words, dyes mordanted by these polymers are apt to discolor under high temperature and humidity conditions.
Furthermore, most of the conventional polymer mordants are water-soluble and diffusible into an image-receiving layer or a layer adjacent thereto, thus causes smearing of images.